[time-nuts] 4046 replacement

[donald collie]

I have 4 frequency synthesiser projects, each using HEF4046BCN`s, but have
recently read that this CMOS IC has a design flaw. What would be a better
chip to retrofit? I`m thinking perhaps a HEF74HC4046AN [that`s if it
doesn`t have the same bug], or a 74HC7046AN - which is similar. Both these
chips are more-or-less pin compatable TIA for any
advice!.......................................................................................................Don

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[Attila Kinali]

On Wed, 18 Apr 2018 20:04:02 +1200

Post by donald collie
I have 4 frequency synthesiser projects, each using HEF4046BCN`s, but have
recently read that this CMOS IC has a design flaw. What would be a better
chip to retrofit? I`m thinking perhaps a HEF74HC4046AN [that`s if it
doesn`t have the same bug], or a 74HC7046AN - which is similar. Both these
chips are more-or-less pin compatable TIA for any

What design flaw are you talking about?

Attila Kinali

[wb6bnq]

Hi Donald,

You could consider the NXP 74HCT9046A as a replacement. It is an
improved version of 4046. However, you do need to study the spec sheet
as it is a bit different, but in a good way.

I have included an attached PDF of the spec sheet, if it makes through
the mail list server.

Bill....WB6BNQ

Post by donald collie
I have 4 frequency synthesiser projects, each using HEF4046BCN`s, but have
recently read that this CMOS IC has a design flaw. What would be a better
chip to retrofit? I`m thinking perhaps a HEF74HC4046AN [that`s if it
doesn`t have the same bug], or a 74HC7046AN - which is similar. Both these
chips are more-or-less pin compatable TIA for any
advice!.......................................................................................................Don
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[donald collie]

Thankyou Attila. I remember reading a book on PLL theory, recently,writen
by a very knowledgable fellow, but I didn`t think to make a copy of his
critique of the 4046. I recall that the nub of it was that the 4046 isn`t
suitable for some applications because of a design flaw. Perhaps somebody
in this group could explain further.
Thankyou Bill, for the datasheet on the 74HCT9046, and your comments
Cheers!..............................................................................Don
jnr ZL4GX

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Post by wb6bnq
Hi Donald,
You could consider the NXP 74HCT9046A as a replacement. It is an improved
version of 4046. However, you do need to study the spec sheet as it is a
bit different, but in a good way.
I have included an attached PDF of the spec sheet, if it makes through the
mail list server.
Bill....WB6BNQ
I have 4 frequency synthesiser projects, each using HEF4046BCN`s, but have

Post by donald collie
recently read that this CMOS IC has a design flaw. What would be a better
chip to retrofit? I`m thinking perhaps a HEF74HC4046AN [that`s if it
doesn`t have the same bug], or a 74HC7046AN - which is similar. Both these
chips are more-or-less pin compatable TIA for any
advice!.....................................................
..................................................Don
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[REEVES Paul]

Hi Donald,

I've just had this problem - the 'signal' input (p14) to the phase detectors is a 'bodge' linear amplifier built around standard CMOS stages and it doesn’t work right. A resistor around a CMOS inverter was a good old recipe to get a 'linear' amplifier stage but this design appears to have a voltage variable resistor of sorts and it gives very strange results. It is fine if used as a CMOS level i/p stage but its use as an ac coupled low level i/p is problematic and may need additional loading. Manufacturer's documentation is scarce and I have only seen one reference to the internal design of this stage. There's quite a bit about it in several places on the net.

Regards,
Paul Reeves G8GJA

-----Original Message-----
From: time-nuts [mailto:time-nuts-***@febo.com] On Behalf Of donald collie
Sent: 18 April 2018 10:40
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] 4046 replacement

Thankyou Attila. I remember reading a book on PLL theory, recently,writen by a very knowledgable fellow, but I didn`t think to make a copy of his critique of the 4046. I recall that the nub of it was that the 4046 isn`t suitable for some applications because of a design flaw. Perhaps somebody in this group could explain further.
Thankyou Bill, for the datasheet on the 74HCT9046, and your comments Cheers!..............................................................................Don
jnr ZL4GX

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Post by wb6bnq
Hi Donald,
You could consider the NXP 74HCT9046A as a replacement. It is an
improved version of 4046. However, you do need to study the spec
sheet as it is a bit different, but in a good way.
I have included an attached PDF of the spec sheet, if it makes through
the mail list server.
Bill....WB6BNQ
I have 4 frequency synthesiser projects, each using HEF4046BCN`s, but have

Post by donald collie
recently read that this CMOS IC has a design flaw. What would be a
better chip to retrofit? I`m thinking perhaps a HEF74HC4046AN [that`s
if it doesn`t have the same bug], or a 74HC7046AN - which is similar.
Both these chips are more-or-less pin compatable TIA for any
advice!.....................................................
..................................................Don
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source=link&utm_campaign=sig-email&utm_content=webmail>
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[John Miles]

Post by REEVES Paul
-----Original Message-----
donald collie
Sent: Wednesday, April 18, 2018 2:40 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] 4046 replacement
Thankyou Attila. I remember reading a book on PLL theory, recently,writen
by a very knowledgable fellow, but I didn`t think to make a copy of his
critique of the 4046. I recall that the nub of it was that the 4046 isn`t
suitable for some applications because of a design flaw. Perhaps somebody
in this group could explain further.
Thankyou Bill, for the datasheet on the 74HCT9046, and your comments
Cheers!..............................................................................Don
jnr ZL4GX

The tristate phase/freq comparator in the original 4046 had a dead-band problem that caused its gain to vary widely as it approached its normal operating point in a stable loop. This wasn't so much a 'bug' as it was a consequence of the fact that there's effectively no gain when there's no phase error to correct.

Ulrich Rohde's book indicates that this problem was first documented in 1978 in an EDN article by some authors named Egan and Clark. Newer PFDs implement the 'antibacklash' logic that Rohde mentions. If you really must use a 4046, I'd look for a newer version whose data sheet explicitly addresses this problem. Better still, use a newer part.

Another workaround is to force the PFD to stay out of its dead zone by loading the output lightly, e.g. with a 1M resistor. You can never compensate for this effect perfectly, though. You can probably expect some downsides like worse reference suppression.

-- john, KE5FX
Miles Design LLC

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[Richard (Rick) Karlquist]

Post by John Miles
Ulrich Rohde's book indicates that this problem was first documented in 1978 in an EDN article by some authors named Egan and Clark. Newer PFDs implement the 'antibacklash' logic that Rohde mentions. If you really must use a 4046, I'd look for a newer version whose data sheet explicitly addresses this problem. Better still, use a newer part.

The book is incorrect. A patent issued in 1976 (US4023116A)
covering the Fairchild 11C44 developed by Eric Breeze predates
the EDN article by several years. I still remember the big
splash the 11C44 made when it was introduced in 1976. The Fairchild
ECL data book had a famous graph comparing it to the MC4044
in the dead zone. In those days, Fairchild and Motorola
were going head to head. I worked on a synthesizer in 1975
that used their brand new at the time 11C90 prescaler.

You can still get 11C44's of a sort by ordering NTE974's
that claim to be a replacement.

Rick N6RK
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[Charles Steinmetz]

Post by Richard (Rick) Karlquist
The book is incorrect. A patent issued in 1976 (US4023116A)
covering the Fairchild 11C44 developed by Eric Breeze predates
the EDN article by several years. I still remember the big
splash the 11C44 made when it was introduced in 1976. The Fairchild
ECL data book had a famous graph comparing it to the MC4044
in the dead zone.

The attached graph is the one I remember. Note that, while the 11C44
was better than the MC4044, neither one was really very linear near zero
error. Good multichip PFD designs of the era outperformed both of them.

Best regards,

Charles

[Magnus Danielson]

Hi,

The book is incorrect.  A patent issued in 1976 (US4023116A)
covering the Fairchild 11C44 developed by Eric Breeze predates
the EDN article by several years.  I still remember the big
splash the 11C44 made when it was introduced in 1976. The Fairchild
ECL data book had a famous graph comparing it to the MC4044
in the dead zone.

The attached graph is the one I remember.  Note that, while the 11C44
was better than the MC4044, neither one was really very linear near zero
error.  Good multichip PFD designs of the era outperformed both of them.

Gardner thrown at them and suggested to use a mixer instead, as it has
better performance.

The real benefit of the 4044 and 4046 lies in that they where CMOS
devices and integrated well with other CMOS devices, and could help to
make designs more compact. If fills a purpose, but does not necessarily
give you optimum performance.

BTW, as you add noise to the signal, much of the behavior of the
triangle or sawtooth shape of the phase-detector average out to that of
a sine, which is no better than that of a mixer, but what happen in the
process is that the phase detector gain changed, and thus the loop
parameters. If you use a mixer, the phase detector gain becomes less
dependent on the S/N and thus a more stable system behavior.

Cheers,
Magnus
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[Richard (Rick) Karlquist]

Post by Magnus Danielson
The real benefit of the 4044 and 4046 lies in that they where CMOS
devices and integrated well with other CMOS devices, and could help to

The original MC4044 is TTL, not CMOS. There is a CMOS "CD4044"
but it is something completely different, not even a phase detector at all.

Rick N6RK
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[Steve Wilson]

Post by Richard (Rick) Karlquist

Post by John Miles
Ulrich Rohde's book indicates that this problem was first documented in 1978 in an EDN article by some authors named Egan and Clark. Newer PFDs implement the 'antibacklash' logic that Rohde mentions. If you really must use a 4046, I'd look for a newer version whose data sheet explicitly addresses this problem. Better still, use a newer part.

The book is incorrect. A patent issued in 1976 (US4023116A)
covering the Fairchild 11C44 developed by Eric Breeze predates
the EDN article by several years. I still remember the big
splash the 11C44 made when it was introduced in 1976. The Fairchild
ECL data book had a famous graph comparing it to the MC4044
in the dead zone. In those days, Fairchild and Motorola
were going head to head. I worked on a synthesizer in 1975
that used their brand new at the time 11C90 prescaler.
You can still get 11C44's of a sort by ordering NTE974's
that claim to be a replacement.
Rick N6RK

I filed patent 3,810,234 on Aug 21, 1972. It includes a dual-d pfd with
variable delay in the feedback path to eliminate deadband. The term
deadband is not included in the patent since it did not exist at the time.
The google url is

https://patentimages.storage.googleapis.com/53/fc/f0/26d83e477e999a/US3810234.pdf

The dual-d is items 24 and 26 on page 4. The feedback is item 58, and the
variable delay is item 28 on the same page. It turns out the delay was not
needed in production since there was no deadband when it was shorted out.

I recall finding an article on the dual-d pfd that was earlier than my
patent but I forget where I found it.

Ignore the name Steve Wilson. That is my online name to foil id theft and
malware.

Mike Monett
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[Steve Wilson]

Post by Steve Wilson
I filed patent 3,810,234 on Aug 21, 1972. It includes a dual-d pfd with
variable delay in the feedback path to eliminate deadband. The term
deadband is not included in the patent since it did not exist at the time.

Sorry, I was mistaken. I explain dead-band on Page 9 of the patent:

"The basic configuration of the phase detector 20 includes two
D-type flip-flops 24 and 26 with feedback to restore both to the
initial state after both have been clocked. A delay 28 in the
feedback path 30 establishes the minimum time that either flip-flop
is in the clocked state, thus establishing a minimum time that
current sources 21a and 21b are switched on. Delay 28 is selected to
insure that both current sources 21a and 21b are first turned fully
on before they are turned off. This feature is necessary to
eliminate dead-band whereby the phase detector 20 does not respond
properly to small phase errors (or time differences) between the two
input signals to the phase detector 20."

This explanation is accurate for symmetrical charge pump delays. The
deadband in the MC4044 is not symmetrical. The DF delay is caused by a
transistor being slow coming out of saturation. This could have been
prevented by applying a Baker clamp around the transistor, or by simply
using diodes to switch the charge pump as was done by CR1 for the UF path.

The transistor in question is Q2 shown on page 5 of the attached MC4044
datasheet.

Also note the DF and UF outputs are shorted together in the datasheet. This
creates a short across VCC on every cycle as both are turned on to reset
the latches.

Post by Steve Wilson
The google url is
https://patentimages.storage.googleapis.com/53/fc/f0/26d83e477e999a/US3810234.pdf
Mike Monett

[Tim Shoppa]

There is no dead time issue at all with 4046 PLL's using the built-in XOR
(Type I) phase detector.

There can be a dead-time issue with 4046 PLL's using the built-in type II
(flip-flop) edge detector.

The 74HCT9046A uses current sources instead of voltage sources in its type
II (flip-flop) edge detector to avoid dead-time issues with this phase
detector.

The Type I phase detector was most commonly used in most 4046 narrowband
PLL applications.

The Type II was mostly used for the applications where the VCO had to track
over most of an octave or more than an octave. Most of these Type II
applications were relatively insensitive to dead time. (Otherwise the
phase-nuts 40 years ago would've noticed. Yes you can hear phase noise even
if they didn't have a good systematic way to measure it back then.)

If your original 4046 circuit has been working fine for the past 40 years
(the 4046 must be 40+ years old now) I see no reason to rip it out and
replace it with the newer variant. You may have trouble finding
through-hole (non-surface mount) 74HCT9046A's at this date anyway.

Tim N3QE

Post by donald collie
Thankyou Attila. I remember reading a book on PLL theory, recently,writen
by a very knowledgable fellow, but I didn`t think to make a copy of his
critique of the 4046. I recall that the nub of it was that the 4046 isn`t
suitable for some applications because of a design flaw. Perhaps somebody
in this group could explain further.
Thankyou Bill, for the datasheet on the 74HCT9046, and your comments
Cheers!.....................................................
.........................Don
jnr ZL4GX
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Post by wb6bnq
Hi Donald,
You could consider the NXP 74HCT9046A as a replacement. It is an

improved

Post by wb6bnq
version of 4046. However, you do need to study the spec sheet as it is a
bit different, but in a good way.
I have included an attached PDF of the spec sheet, if it makes through

the

Post by wb6bnq
mail list server.
Bill....WB6BNQ
I have 4 frequency synthesiser projects, each using HEF4046BCN`s, but

have

Post by wb6bnq

Post by donald collie
recently read that this CMOS IC has a design flaw. What would be a

better

Post by wb6bnq

Post by donald collie
chip to retrofit? I`m thinking perhaps a HEF74HC4046AN [that`s if it
doesn`t have the same bug], or a 74HC7046AN - which is similar. Both

these

Post by wb6bnq

Post by donald collie
chips are more-or-less pin compatable TIA for any
advice!.....................................................
..................................................Don
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[Clint Jay]

Why not try one, the 74HC4046 is pin compatible I think, you may need to
make some changes to use the '7046 version but you can then make a value
judgement if the flaw had in fact mainfested itself as a problem in your
design?

Post by donald collie
I have 4 frequency synthesiser projects, each using HEF4046BCN`s, but have
recently read that this CMOS IC has a design flaw. What would be a better
chip to retrofit? I`m thinking perhaps a HEF74HC4046AN [that`s if it
doesn`t have the same bug], or a 74HC7046AN - which is similar. Both these
chips are more-or-less pin compatable TIA for any
advice!.....................................................
..................................................Don
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[Jim Harman]

While we are on the subject of the 74HC4046, I would like to point out a
confusing error in the TI datasheet for this part, found at
http://www.ti.com/lit/ds/symlink/cd74hc4046a.pdf

The waveform diagram for Phase Comparator 3, Fig. 7 on p. 5, has inverted
waveforms for PC3out and VCOin. PC3out should rise at the leading edge of
SIGin and fall at the leading edge of COMPin. The corresponding diagram in
the NXP/Phillips datasheet, Fig. 11, is correct.

Post by Clint Jay
Why not try one, the 74HC4046 is pin compatible I think, you may need to
make some changes to use the '7046 version but you can then make a value
judgement if the flaw had in fact mainfested itself as a problem in your
design?

--Jim Harman
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[EB4APL]

Hi,

When I was going to build a Brooks Shera's GPSDO in 2009, I ordered from
him some parts that I needed. He graciously added a couple of Texas
Instruments' 74HC4046AE that was used in the phase detector because,
according to him, these parts from other manufacturers would not work
correctly.

Regards,

Ignacio, EB4APL



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[Charles Steinmetz]

Post by donald collie
HEF4046BCN`s, but have
recently read that this CMOS IC has a design flaw. What would be a better
chip to retrofit?

As Bill said, the HCT9046 is the improved version of the 4046.

The "flaw" in the 4046 is a dead zone around zero error in Phase
Comparator 2 (the PC one generally uses). PC2 in the HCT9046 uses
charge-pump outputs that are biased to avoid the dead zone. It also
uses an internal voltage reference, rather than fraction-of-Vdd, to
minimize drift.

Note that the 9046 is HCT only (no HC version), meaning that its input
transition points are TTL standard (not 1/2 Vdd, like normal CMOS logic
such as HC).

Also note that the HCT9046 has only two phase comparators (PC1 and PC2),
and does not have the 4046's PC3 (this is true also of the various 7046
chips, although they do not share the dead-zone improvement of the 9046).

Best regards,

Charles


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[Magnus Danielson]

Post by Charles Steinmetz

Post by donald collie
HEF4046BCN`s, but have
recently read that this CMOS IC has a design flaw. What would be a better
chip to retrofit?

As Bill said, the HCT9046 is the improved version of the 4046.
The "flaw" in the 4046 is a dead zone around zero error in Phase
Comparator 2 (the PC one generally uses).

It is very bad indeed. Someone chose to use the 4046 to lock up a 155,52
MHz VCXO to a 8 kHz reference, using a 4046 as a core. The charge-pump
was then "accelerated" with a supposedly better charge-pump with a ton
of passives. Turns out that the dead-band was still there to haunt the
designers. The 155,52 MHz was further multiplied to become the 2,48832
Gb/s clock, and as they measured this they had problems with the
jitter/wander of it, as they measured on a rented instruments. Then they
called me in for it. I looked at it and could quickly conclude that the
problem was the dead-band, so that the VCXO coasted up and down after
the push in either side due to the deadband, creating jitter/wander
breaking the standard limits. I concluded that a more continuous
approach was needed, and then they went back to the S/R FF I had
originally proposed, which they natually had ignored and overengineered
something else, and well, look and behold it locked and was well within
margin.

4046 can be cool and nice little critters, but use them wisely where
they work. I try to steer clear from the charge-pump whenever I can.

Post by Charles Steinmetz
  PC2 in the HCT9046 uses
charge-pump outputs that are biased to avoid the dead zone.  It also
uses an internal voltage reference, rather than fraction-of-Vdd, to
minimize drift.

I was about to recommend having a look at the HCT4046, HCT7046 and
HCT9046 series, if one needs something in that family.

Rather than doing charge-pump, an op-amp setup for a integrator in a
PI-loop and a reasonable continuous waveform comparator of choice do
really well. XOR, S/R FF or mixer. The more I work on PLLs, the simpler
they become and the robuster they seem to become.

Cheers,
Magnus
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[Charles Steinmetz]

See below for further information on working with the 4046/7046/9046 PLL
families, including must-have design tools for anyone designing with
these devices.

Post by Magnus Danielson

Post by Charles Steinmetz
The "flaw" in the 4046 is a dead zone around zero error in Phase
Comparator 2 (the PC one generally uses).

It is very bad indeed. Someone chose to use the 4046 to lock up a 155,52
MHz VCXO to a 8 kHz reference, using a 4046 as a core. The charge-pump
was then "accelerated" with a supposedly better charge-pump with a ton
of passives. Turns out that the dead-band was still there to haunt the
designers. The 155,52 MHz was further multiplied to become the 2,48832
Gb/s clock, and as they measured this they had problems with the
jitter/wander of it

Of course the dead zone was still there -- it is built into the
4046/7046 phase comparator, and nothing you do after-the-fact can
eliminate it (but see below re: linearizing the 4046/7046 phase
comparator). Most of what is wrong with the circuit you describe above
is simply bad system design, not any fault of the 4046.

While it is true that some people call the PC2 output of the 4064 a
"charge pump," as a voltage source it is, at best, a very poor one. The
9046 has a real, current-mode charge pump with tri-state outputs. The
attached charts show the difference in linearity [1].

There are tricks one can pull to linearize the PC2 output of a 4046 or
7046. In particular, (i) injecting current into the PC2 output node
biases the detector away from the dead zone at the price of a static
phase error, and (ii) instead of using a passive RC filter, run the PC2
output through the resistor to the virtual-ground input of an active
filter, which effectively turns the PC2 voltage output into a bipolar
current output. Still, however, the 4046/7046 PC2 cannot overlap
positive and negative steering pulses as the 9046 PC2 can, and the 9046
thresholds are established by a real voltage reference, so the 9046 will
always be better than the best that can be done with a 4046 or 7046.

I do not use 4046-type devices very often, but ever since the 9046
became available I have used it exclusively in preference to the 4046
and 7046.

Best regards,

Charles


[1] The attached charts are taken from the Philips CMOS PLL Designer's
Guide (1995), which is an absolute must-have for anyone designing with
the 4046/7046/9046 PLL families. List member Daniel Mendes pried the
Guide and supporting files out of Philips a couple of years ago, and
list member Oz from DFW hosts them on his site. I cropped the pages of
the Design Guide to eliminate the large white borders and re-posted it
all as a zip file to Didier's site:
<http://www.ko4bb.com/getsimple/index.php?id=download&file=03_App_Notes_-_Proceedings/74HC4046_7046_9046_CMOS_PLL_design_guide_and_files_Philips_1995.zip>.
Enjoy!

[Alexander Pummer]

but as I wrote a while ego ADI has a bit different chip which is free of
dead zone and much faster, I used it for low phase-noise clock generator
for 3,1Gb/s fiber optic systems of C-Cor/Comlux in the end of the past
century, now I am on vacation and do not have my engineering note books
with me, but 1) I already posted it in the past 2) I will post it again
after I returned home,
73
KJ6UHN

Post by Charles Steinmetz
See below for further information on working with the 4046/7046/9046
PLL families, including must-have design tools for anyone designing
with these devices.

Post by Magnus Danielson

Post by Charles Steinmetz
The "flaw" in the 4046 is a dead zone around zero error in Phase
Comparator 2 (the PC one generally uses).

It is very bad indeed. Someone chose to use the 4046 to lock up a 155,52
MHz VCXO to a 8 kHz reference, using a 4046 as a core. The charge-pump
was then "accelerated" with a supposedly better charge-pump with a ton
of passives. Turns out that the dead-band was still there to haunt the
designers. The 155,52 MHz was further multiplied to become the 2,48832
Gb/s clock, and as they measured this they had problems with the
jitter/wander of it

Of course the dead zone was still there -- it is built into the
4046/7046 phase comparator, and nothing you do after-the-fact can
eliminate it (but see below re: linearizing the 4046/7046 phase
comparator). Most of what is wrong with the circuit you describe above
is simply bad system design, not any fault of the 4046.
While it is true that some people call the PC2 output of the 4064 a
"charge pump," as a voltage source it is, at best, a very poor one.
The 9046 has a real, current-mode charge pump with tri-state outputs.
The attached charts show the difference in linearity [1].
There are tricks one can pull to linearize the PC2 output of a 4046 or
7046. In particular, (i) injecting current into the PC2 output node
biases the detector away from the dead zone at the price of a static
phase error, and (ii) instead of using a passive RC filter, run the
PC2 output through the resistor to the virtual-ground input of an
active filter, which effectively turns the PC2 voltage output into a
bipolar current output. Still, however, the 4046/7046 PC2 cannot
overlap positive and negative steering pulses as the 9046 PC2 can, and
the 9046 thresholds are established by a real voltage reference, so
the 9046 will always be better than the best that can be done with a
4046 or 7046.
I do not use 4046-type devices very often, but ever since the 9046
became available I have used it exclusively in preference to the 4046
and 7046.
Best regards,
Charles
[1] The attached charts are taken from the Philips CMOS PLL
Designer's Guide (1995), which is an absolute must-have for anyone
designing with the 4046/7046/9046 PLL families. List member Daniel
Mendes pried the Guide and supporting files out of Philips a couple of
years ago, and list member Oz from DFW hosts them on his site. I
cropped the pages of the Design Guide to eliminate the large white
<http://www.ko4bb.com/getsimple/index.php?id=download&file=03_App_Notes_-_Proceedings/74HC4046_7046_9046_CMOS_PLL_design_guide_and_files_Philips_1995.zip>.
Enjoy!
---
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[Charles Steinmetz]

Post by Alexander Pummer
but as I wrote a while ego ADI has a bit different chip which is free of
dead zone and much faster

Hell, there are literally hundreds of PLL chips, lots of them better at
various things than the 4046. I did not suggest that the 4046/7046/9046
is the best PLL for any particular purpose (and I did say I rarely use
them). My points were just (i) that the 4046 doesn't perform as
terribly as a lot of people seem to think if you know a few easy tricks,
and (ii) that the 9046 is better on all counts without the need for such
tricks.

It seems that lots of people like the 4046 series chips (including the
7046 and 9046), partly due to familiarity, partly because there are
thousands of published circuits that use them and not everybody wants to
completely redesign circuits that are already known to work, and
certainly because they are dirt cheap (unlike the fancier Analog Devices
parts, some of which are quite pricey). I thought these folks might
like to know how to optimize performance with the 4046/7046/9046 series,
and to be reminded about the design tools available for them.

Charles


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[Magnus Danielson]

Hi,

Post by Charles Steinmetz

Post by Alexander Pummer
but as I wrote a while ego ADI has a bit different chip which is free of
dead zone and much faster

Hell, there are literally hundreds of PLL chips, lots of them better at
various things than the 4046.  I did not suggest that the 4046/7046/9046
is the best PLL for any particular purpose (and I did say I rarely use
them).  My points were just (i) that the 4046 doesn't perform as
terribly as a lot of people seem to think if you know a few easy tricks,
and (ii) that the 9046 is better on all counts without the need for such
tricks.
It seems that lots of people like the 4046 series chips (including the
7046 and 9046), partly due to familiarity, partly because there are
thousands of published circuits that use them and not everybody wants to
completely redesign circuits that are already known to work, and
certainly because they are dirt cheap (unlike the fancier Analog Devices
parts, some of which are quite pricey).  I thought these folks might
like to know how to optimize performance with the 4046/7046/9046 series,
and to be reminded about the design tools available for them.

Well, my point was that I have seen it bite, but there is other
occasions where it doesn't bite. Still, better options can many times be
used, and many designs it can be good enough. If you use it without care
and knowledge, beware. That goes for any tool we apply, so bringing up
attention is already there a step on the way.

Cheers,
Magnus
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[Charles Steinmetz]

If you use it without care and knowledge, beware. That goes for any tool we apply

Indeed! The Cardinal Rule of design! (So often unfollowed....)

"An engineer is someone who can figure out what questions need to be
asked, figure out how to answer them, and tell when they are correctly
answered."

Best regards,

Charles


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[Magnus Danielson]

Hi Charles,

If you use it without care and knowledge, beware. That goes for any tool we apply

Indeed!  The Cardinal Rule of design!  (So often unfollowed....)
"An engineer is someone who can figure out what questions need to be
asked, figure out how to answer them, and tell when they are correctly
answered."

Indeed. I don't claim to be expert on the 4046 family of PLL chips, but
at least I can share my experience and let you know about the things I
learned from being bitten.

Then, reading Gardners book, and advancing to full PI loop, I feel more
comfortable about mixer or S/R-gate loops. The "magic" of some detectors
have become less of a benefit for many designs. In general, most of my
designs have become much simpler and robust. However, it's always good
to have alternatives.

Cheers,
Magnus
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[donald collie]

Question : In the 74HCT9046BCN - does a high on the inhibit line Knobble
the P/F detectors as well as the VCO?

Thankyou to all who responded to my querie - I`ve got 5 74HCT9046BCN on a
slow boat from China. They will retrofit the projects where I used a 4046
without much pcb surgery. PLL`s are fun, especially when yo can watch them
lock on a Tek 7834 :-) I interloaned the weighty tome again, and am
having another read - it is "Phase Locked Loops : Design, Simulation, and
Applications" sixth edition - a good bedtime read!
Cheers!.....................................................................Don
C. ZL4GX
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On Mon, May 7, 2018 at 6:11 AM, Magnus Danielson <

Post by Magnus Danielson
Hi Charles,

Post by Charles Steinmetz

If you use it without care and knowledge, beware. That goes for any tool we apply

Indeed! The Cardinal Rule of design! (So often unfollowed....)
"An engineer is someone who can figure out what questions need to be
asked, figure out how to answer them, and tell when they are correctly
answered."

Indeed. I don't claim to be expert on the 4046 family of PLL chips, but
at least I can share my experience and let you know about the things I
learned from being bitten.
Then, reading Gardners book, and advancing to full PI loop, I feel more
comfortable about mixer or S/R-gate loops. The "magic" of some detectors
have become less of a benefit for many designs. In general, most of my
designs have become much simpler and robust. However, it's always good
to have alternatives.
Cheers,
Magnus
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[Charles Steinmetz]

Post by donald collie
Question : In the 74HCT9046BCN - does a high on the inhibit line Knobble
the P/F detectors as well as the VCO?

I've never had occasion to use the INH pin. The 2009 NXP datasheet says
it shuts down the whole circuit:

"The inhibit function differs. For the 74HCT4046A a HIGH-level at the
inhibit input
(pin INH) disables the VCO and demodulator, while a LOW-level turns both
on. For
the 74HCT9046A a HIGH-level on the inhibit input disables the whole
circuit to
minimize standby power consumption."

Best regards,

Charles


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[Bob kb8tq]

Hi

If this is a new build, why use a 4046 in the first place? There are many newer parts
that will do all sorts of things. If this is a repair of something that has been running
for years, is it > 5V supply to the chips? If so, you are pretty much stuck with 4000
series CMOS.

There are no fatal flaws in the 4046, but there are basic design limitations. Those
have been well documented over the years and here on the list. Going to a better
part is the answer for that stuff ( = get away from any xxxx4046 IC).

Bob

Post by donald collie
I have 4 frequency synthesiser projects, each using HEF4046BCN`s, but have
recently read that this CMOS IC has a design flaw. What would be a better
chip to retrofit? I`m thinking perhaps a HEF74HC4046AN [that`s if it
doesn`t have the same bug], or a 74HC7046AN - which is similar. Both these
chips are more-or-less pin compatable TIA for any
advice!.......................................................................................................Don
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[Richard (Rick) Karlquist]

Post by Bob kb8tq
Hi
If this is a new build, why use a 4046 in the first place? There are many newer parts
that will do all sorts of things. If this is a repair of something that has been running
for years, is it > 5V supply to the chips? If so, you are pretty much stuck with 4000
series CMOS.
There are no fatal flaws in the 4046, but there are basic design limitations. Those
have been well documented over the years and here on the list. Going to a better
part is the answer for that stuff ( = get away from any xxxx4046 IC).
Bob

Any 4000 series CMOS, besides being extremely slow (prop
delay measured in MICROseconds), have a totem pole output
that momentarily short circuits the power supply when
switching and generates tremendous EMI.

I once wasted several weeks of time running down a spur
problem that I eventually traced to a 4XXX frequency divider.

Rick N6RK

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[Tisha Hayes]

I too would recommend the 74HCT9046A instead of the 4046.

The data sheet is here;
https://assets.nexperia.com/documents/data-sheet/74HCT9046A.pdf

*Ms. Tisha Hayes*

Post by Bob kb8tq
Hi
If this is a new build, why use a 4046 in the first place? There are many newer parts
that will do all sorts of things. If this is a repair of something that has been running
for years, is it > 5V supply to the chips? If so, you are pretty much stuck with 4000
series CMOS.
There are no fatal flaws in the 4046, but there are basic design limitations. Those
have been well documented over the years and here on the list. Going to a better
part is the answer for that stuff ( = get away from any xxxx4046 IC).
Bob

Post by donald collie
I have 4 frequency synthesiser projects, each using HEF4046BCN`s, but

have

Post by donald collie
recently read that this CMOS IC has a design flaw. What would be a better
chip to retrofit? I`m thinking perhaps a HEF74HC4046AN [that`s if it
doesn`t have the same bug], or a 74HC7046AN - which is similar. Both

these

Post by donald collie
chips are more-or-less pin compatable TIA for any
advice!.....................................................

..................................................Don

Post by donald collie
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[Anton Moehammad via time-nuts]

Hi All, I interested in discussion about 4046, in lars GPSDO he use 4046 as phase comparator must I replace this Chip for CD74HCT4046A btw I also have many TC5081 I wonder how to test the circuit use this chip if have same problem with 4046.Thank YouAnton
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[Ulrich Rohde via time-nuts]

 
Maybe of interest.....here are the measured phase noise data in dB/Hz1Hz 86.3    10Hz 134.49 Hz    100Hz 139.99    1k 140.1    10k 140.1 100k 144.7273 de N1UL
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